90 H. M. AYOODCOCK. 



ovala,coufirms Paehler's account with regard to the absolute 

 ao-reeraent in appenrance between the conjugating elements. 

 He finds, moreover, that the process of nuclear maturation 

 described by that author (see footnote, p. 51) occurs equally 

 in both kinds. Hence in this form there is complete 

 isogamy. It is interesting to note that in Monocystis this 

 nuclear reduction is apparently delayed, Brasil having 

 observed it to take place in the zygotes. Another point 

 noticed by Schnitzler is the occurrence of two kinds of cyst, 

 containing respectively small and large spores (micro- and 

 mega-spores). As the author surmises, this fact may perhaps 

 stand in relation with the occurrence of solitary as well as 

 common encystment and sporulation. 



Lastly, Crawley ('Amer. Nat.,' September, 1905, p. 607) 

 derives the Telosporidia (i.e. Coccidia, Htemosporidia, and 

 Monocystid Gregarines) from a Polycystid Gregarine. As 

 will be seen on referring to page 71 et seq. above, I do not 

 concur with this view. The ancestral Gregarine (derived 

 from a " gregariniform " Flagellate) was probably not so 

 highly differentiated and specialised morphologically as the 

 Polycystids now are. These are rather to be looked upon as 

 constituting one line of descent, the Monocystids another. 

 The Haemosporidia and Coccidia, again, have branched off in 

 other directions from the ancestral Flagellate. 



January, 1906. 



Analysis of Contents. 

 Preface, p. 1. 



(1) Introduction, p. 3. 



(2) Methods. 



[a] Examination, p. 6. 



{b) Fixation and staining, p. 7. 



(c) Attempts at artificial infection, p. 9. 



(3) Habitat and mode of life. 



(a) C. irregularis, p. 11. 



Histology of the vascular network, p. 11. 

 Relation of the parasites to the blood-vessels, p. 12. 



